Time relay



O. WELLE TIME RELAY Feb. 7, 1939.

Filed NOV. 10, 1936 Fig.1.

INSULATION INSULHTiflN Fig.2..

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inventor: Otto V\/e\ 1e His A'btorrwey- Patented Feb. 7.193s 2,146,608

UNITED STATES PATENT OFFICE TIME RELAY 'Otto Welle, Berlin-Lichtenberg, Germany, assignor to General Electric Company, a corporation of New York Application November 10, 1936, Serial No. 110,179 In Germany December 16, 1935 12 Claims. (Cl. 200116) My invention relates to time relays, more parabruptly rotating so as to return the other conticularly to thermal time relays in which the tact to its normal position.

contact operation is controlled by a heat respon- For a more complete understanding of my inslve thermal element and has for an object the vention, reference should now be had to the drawprovision of a simple and reliable device of this ing, in which Fig. 1 is a diagrammatic elevational type.

Thermal time relays have heretofore been vention, and Fig. 2 is a circuit diagram illustratstrip, the heating circuit of which is energized Referring now to Fig. 1', the thermal time relay to initiate a timing interval at the expiration of shown comprises a base ID from which extends which the heating circuit is interrupted. During a pin l I for pivotally mounting a support or block energization of the heating circuit, the thermal l2 on which is carried-a. bimetallic thermal eleelement flexes so as to effect closure of the cirment l3. The upper free end of the thermal H cult controlling contacts and upon de-energizaelement I3 is interposed in'the path of movement 1 tion of theheatinglcircuit, the thermal element of a latch l4 which extends outwardly from a cools and returns to its normal position to open second support pivotally mounted on a pin it. the contacts. In such devices, however, the con- As shown, the latch i4 carries an angle piece I! tacts open slowly due to the gradual cooling of along which lies a conducting spring I8, the lower the thermal element and accordingly sparking v end of which supports a movable contact i9. Arand burning of the contacts occur. Accordingly, ranged for co-operation with the contact [9 is a it is a further object of my invention to provide second movable contact 20 which is supported on a thermal time relay in which the closing and a conducting arm 2| carried by the support i2. opening movement of the contacts takes place In order to bias the contacts l9 and 20 for means for interrupting the heating circuit upon strained in one position by engagement of the closure of the contacts and means influenced by latch I4 with the thermal element l3 and the the thermal element for abruptly opening the movable contact 20 is restrained in a second contacts a predetermined time after the heating position by engagement of the arm 2| with an 35 circuit is interrupted. More particularly, the adjustable stop 24. An additional spring is circuit controlling contacts are biased for moveprovided for assisting the spring 22 in biasing ment from one position to a second position, one the support i 2 for counterclockwise movement of the contacts being restrained in the one posiabout its pivot.

4 tion by the thermal element which is'mounted on As will be explained more fully in connection is carried by this pivotal support and therefore to a suitable load 3| a pivotal support. Upon a predetermined change with Fig. 2, a pair of conducting leads 26 and 21 40 A ply conductor 30 and the lead-in this position, the pivotal support thereupon conductor 29 is connected to a control switch 34,

circuit position heating unit may I one terminal of which is, connected by a conductor 35 to the supply conductor 33.

Although any suitable type of control switch may be provided, I have shown for purposes of illustration a switch having a movable contact blade 36 which is manually operable from an open (shown in heavy lines) to a closed circuit position (shown in dotted lines) and which is provided 'th a biasing spring 31 which selectively biases the contact blade to either of its positions. It will be understood, of course, that while I have shown the thermal element l3 connected directly in an energizing circuit, a separate be provided connected in the energizing circuit and disposed adjacent the thermal element.

Upon closure of the control switch 3% and the consequent heating of the thermal element I3, the upper free end of the thermal element moves in a right-hand direction, as viewed in Fig. 1, until it moves clear of the latch IQ and releases the latch for movement in a clockwise direction about the pivot l6 under the bias of the spring 22 so as to move the contact l9 from the position shown in the drawing into engagement with the contact 20. Closure of the contacts l9 and 2|! completes the load circuit and energizes the trip coil 32, whereupon a plunger 38 associated with the trip coil is operated to move the contact blade 36 from its closed position to its open circuit position and thus interrupt the heating circuit of the I thermal element i3.

'The thermal element i3, of course, begins to cool as soon as its energizing circuit is interrupted, but it will now be observed that the end of the latch I4 is disposed in the path of the thermal element so as to prevent the free end thereof from returning to its normal position. Even though the free end of the thermal element strained against movement to its normal position, the thermal element straightens out as'it cools and thus effects rotation of the clockwise direction about the pivot l and accordingly the contact 20 moves in a right-hand direction so as to return the contact Is to its original position.

As the contact I9 is moved in'a right-hand direction by the contact 2|], the latch I4 is raised and as soon as the contact |9 reaches its original position, the free end of the thermal element l3 will be released, whereupon the support |2 will ,be abruptly rotated in a counterclockwise direction by the spring 22 to return the thermal element l3 to its latching position and to returnthe contact 20 to its normal position shown, thus abruply separating the contacts l9 and 2D.

It will be apparent that the closing and opening time of the thermal relay may be varied simply by adjusting the member 24 so as to very the gap between the contacts |9 and 20 and to vary the initial position of the thermal element l3. In some cases it is desired to compensate for variations in the ambient temperature conditions and this may be accomplished by forming the arm 2| of bimetallic material, as shown in Fig. 2. When this arm 2| is formed-of bimetallic material, the conducting lead 21 should, of course, be connected either directly to the contact 2|! or to the arm 2| closely adjacent the-contact 20 so that theload current flowing through the contacts will not heat the arm 2|.

When this arm 2| is formed of bimetallic material, it will be apparent that a change in'ambient temperature tending to move-the free end of the thermal element |3 in a right-hand direction so as to decrease the degree of latching between the element l3 and the latch M will also eflect right-hand movement of the free end of the arm 2|. Since the springs 22 and 25 are arranged to maintain the free end of the arm 2| in engage- 24, the support |2 will be rotated about its pivot H to maintain the proper degree of latching between the thermal element i3 and the latch l4. Similarly, if the ambient temperature conditions tend to efiect movement of the free end of the thermal element l3 in a left-hand direction, the corresponding fiexure of the arm 2| will efiect clockwise rotation of the support l2 to maintain the free end of the thermal element l3 in its proper latching position.

Although I'have shown a thermal relay in which the contacts are closed a predetermined time after the thermal element I3 is heated, it will, of course, be understood that the relay'may be so arranged as to close the contacts when the thermal element is cooled and to open the contacts again when the thermal element is heated. Thus, a temperature change of one sense effects closing of the contacts while a temperature change of an opposite sense efiects opening of the contacts.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limted thereto, since many modifications may be made andI, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A thermal time relay comprising a pair of relativelymovable contacts, a thermal element, means for establishing a heating circuit for said thermal element, means-influenced by said thermal element for moving one of said contacts with a snap action to abruptly close said contacts a predetermined time after said heating circuit is established, means responsive to closure of said contacts for interrupting said heating circuit, and'means influenced by said thermal element for moving one of said contacts with a snap action to abruptly open said contacts a predetermined time after said heating circuit is interrupted.

2..-A thermal time relay comprising 'a contacts, means biasing said contacts for movement from one position to a second position, a thermal element, means for' establishing a heating circuit for said thermal element, means including said thermal element ing one of said contacts in said oneposition and pair of for normally latchfor releasing said one contact for movement to said second position abruptly to engage the other a of said contacts a predetermined time afterzsaid heating circuit is established, means responsive to closure of said contacts for interrupting said heating circuit, and means including said thermal element for moving saidpair of contacts .to said one position as said thermal'element cools, whereuponsaid one contactis latched in saidone position and said other contact is released for abrupt movement to said second position thereby to open said contacts a predetermined time after closure thereof.

3. A thermal time relay comprising a of contacts, means biasing said contacts for movefor releasing said one contact for movement to in said one position and to return said other consaid second position abruptly to engage the other tact quickly to said second position, and means for 6 heating circuit, means including said thermal ele- 7. A thermal relay comprising a pair of conment for moving said pair of contacts to said one tacts, means lasing said contacts for movement position as said thermal element cools, wherefrom one position to a second position a thermal 10 position and said other contact is released for eluding said thermal element for norma ly l ch- 10 contact ar clos d and opened thermal element, means including said thermal 15 4. A thermal time relay comprising a pair of element for simultaneously moving said pair of m circuit for said thermal element, means inposition by said thermal element and said other 20 said second position abruptly to engage the other pivoted supp r a Pa r O o e t ve y of said contacts a predetermined time after'said Carried y Said pp means blaslng Said D- 25 position as said thermal element cools, whereupon With its free end disposed in the path of move- 30 thereof, adjustable means for varying said desaid latch to release said support and its contact 35 M 5. A thermal relay comprising a pairof conreturning to its normal position whereby said w of said contacts, and means including said thertact in said one position. 59

, tacts, means biasing said contacts for movement contacts for interrupting said heating circuit, 60

; said projection thermal element for moving the other of said contacts to disengage said first contact a predetermined time after said heating circuit is interrupted.

11. A thermal time relay comprising a pair of pivotally mounted supports, a-thermostatic strip secured at one end to a first of said supports, a first contact mounted on said first support, a second cooperating contact mounted on the second of said supports, means biasing each of said supports for movement of each of said contacts from a first position in engagement with the other of said contacts to a second position in engagement with the other of said contacts, a

latching projection on said second support nor-' mally engaged by the end of said thermostatic strip to hold said second contact in its first position, means for heating said strip to cause it to flex and thereby disengage said projection for movement of said second contact to said second position into engagement with said first contact, moving into the path of said strip, whereby when said strip cools it flexes to move said contacts to said first positions whereby said projection is moved out of the path of said strip to release said first contact for movement back to its second positionto separate said contacts, said strip then engaging said projection to hold said second contact in' said first position:

12. A thermal time relay comprising a pair of pivotally mounted supports, a pairof bimetallic thermostats each secured at one end to a first of said supports, a first contact mounted on the end of a first of said thermostats, a second cooperating contact mountedon the second of said supports, means biasing each of said supports for movement of each of said contacts from a first position in engagement with the other of said contacts to a second position in engagement with the other of said contacts, a latching projection on said second support normally engaged by the end of the second of said thermostats to' hold said second contact in its first position against its bias, said first contact being then in its second position, means for heating said second thermostat to cause it to fiex and thereby disengage said projection and release said second support for movement of said second contact to said second position into engagement with said first contact, said projection moving into the path of said second thermostat, means responsive to engagement of said contacts for interrupting said heating means whereupon said second ther mostat cools and fiexes to move said first support said contacts and, said second support together projection is the path of said second thermostat to release said first support which accordance with its bias to move said first contactaback to. its second position to separate said contacts, said second thermostat then engaging said projection to hold said second contact in its first position.

" OTTO WELLE. 

